All the world’s a stage for the Russian aristocrats in the latest adaptation of Leo Tolstoy’s “Anna Karenina.” But if it’s only a play, why should we care?

Setting the action primarily in a decaying theater, director Joe Wright, working from a screenplay by playwright Tom Stoppard, has made a film about a society in decline. If you are expecting a passionate romance between an adulterous wife and a young, mustachioed soldier, you are advised to look elsewhere.

As he did in his adaptations of “Pride & Prejudice” and “Atonement,” Wright calls on his muse, Keira Knightley. Here she goes where Greta Garbo, Vivien Leigh and Jacqueline Bisset have gone before, playing Anna, the wife of a stiff government official (Jude Law).

Anna meets the allegedly dashing Count Vronsky (Aaron Taylor-Johnson) in a train station on her way to mend the marriage of her brother Oblonsky (Matthew Macfadyen, who played opposite Knightley in “Pride & Prejudice”), who also has a wandering eye. Meanwhile, Oblonsky’s idealistic friend Levin (Domhnall Gleeson) is carrying a torch for Oblonsky’s sister-in-law Kitty (Alicia Vikander), who is in love with Vronsky.

These are parallel storylines, but the movie seems to forget about one, then the other.

Knightley’s Anna is a brittle, flighty bird who takes one glance from a younger man as an excuse to fly the coop. But it’s Taylor-Johnson (formerly Johnson in “Kick-Ass” and “Savages”), his hair streaked like George Michael circa Wham!, who’s fatal — neither seductive enough to lure a woman away from Law (even without most of his hair) nor a compelling screen presence in his own right. He and Knightley are well-matched in eyebrows, but that’s about it.

They are upstaged by the theater in which their characters dally, with its rolling sets, painted backdrops, glowing footlights and stage doors that slide open onto a frozen tundra. It’s the sort of expansive, impossible stage Esther Williams might have aquacaded on, allowing Wright to both investigate every nook of a confining space, as he did in the Tallis’ house in the first half of “Atonement,” and indulge his predilection for long pans, as in that film’s five-minute Dunkirk beach Steadicam shot. Here the pans are 360-degree meticulously choreographed marvels.

Then there’s the actual choreography, by Belgian contemporary dance choreographer Sidi Larbi Cherkaoui, who gets equal billing with ace cinematographer Seamus McGarvey and composer Dario Marianelli. A roomful of clerks stands and sits in a dance of futility, stamping documents in time with the music. Anna and Vronsky’s first dance incorporates an intricate, voguey forearm jive. (The anachronisms are extended to Anna’s forward-looking wardrobe: 1870s Paris couture on the bottom, 1950s Balenciaga on top.)

But the theatrical conceit distances the audience from the characters, reminding us that it’s only a play. Under these straitened circumstances it’s only Law who moves; Gleeson (who played Bill Weasley in the “Harry Potter” films) also makes an impression, but he has the advantage of playing the character who spends the least amount of time in the theater.

Like its rebellious heroine, Wright’s costume drama may flout the rules, but it’s as chilly as the Siberian steppe.

(At the Rio, Tivoli and Town Center.)